In the related art, it is known that a semiconductor device covered with a resin mold is to be placed in a metallic case having a radiation unit such as a fin (for example, see JP 2010-10505 A). A placement base is provided inside a case, and a semiconductor device is placed on this placement base. The semiconductor device placed on the placement base is fixed to a fixing unit by a fastener member and the like. In some cases, a warp of the semiconductor device fixed to the fixing unit or a warp of a surface of the placement base leads to disadvantages.